Synchronism-indicator



(NoV Model.) l

- lL. BELL.

SYNGHRONI-SM,INDICATOR.

No. 502,695. Patented Aung. 8,1893.

WITNESSES. MQW. W,

1Q STATES lPATENT OFFICE.

LOUIS BELL, OE BOSTON, MASSACHUSETTS, ASSIGNOR vTo THE GENERAL ELEOTRIO COMPANY, OE NEw YORK.

SYNCHRONIS M|N DICATOR.

SPECIFICATION forming part of Letters Patent No. 502,695, dated August 8, 1893. l

Appiieeeen mea neeember 24,1892e Serin neeeas. (remede.)

To all whom it may concern:

Be it known that I, LOUIS BELL, a citizen-of the United States, residing at Boston,county of Suffolk, State of Massachusetts, have invented a certain new and usefullmprovement in Synchronism-Indicators, of which the following is a specification.

It is already well known to those skilled in running dynamo electric machines that whenever two or more machines of the alternating current type are to be coupledlup together, as for example, when two dynamos connected in multiple are to feed a common circuit, or one dynamo is to drive another as a motor,it is necessary to bring the machines to synchronism before they are thrown into circuit with one another, else they will not work prop'- erly. Hence it is a necessary adjunct of an installation of this character to have some means by which the attendant can readily detect when the machines are running at the s311119 Speed, or synchronously as it is called, for though synchronism properly implies, both, equal periodicity of currentwave lengths resulting from equality-of speed, and har.

mony in phase as well, yet the term as here used refers more particularly tofequality in speed, asthe essential thing from a practical standpoint is that the wave lengths have equal periods, for then any lack of harmony in phase will right itself even if exact harmony does notatrst exist. vices have been heretofore used to detectthe presence or absence of this necessary Vsyn- My present invention comprises another and radically different method of accomplishing this same result which I prefer to use, and

which gives the desired indication to the ear are produced whose periods tally exactly with the current periods. By this transposition of current waves into sound waves of correspond- Phase lamps and other de` ing periodicity a tone of distinctive pitch can be'secured for any given machine when running at a given speed. When dealing with two or more machines this reproduction in sound waves of the current waves of the machines enables the ready detection of any departure from equal periodicity for, as is well known, the combined effects of two such series of sound waves are to give rise to a steady tone if the sound periods are equal, but if unequal the interference of the waves causes sudden swellings or reinforcements of sound at regular intervals known as beats Inl my present invention lack of synchronism is detectedl by the presence of sound lwaves having periods corresponding to the current periods of the lrespective machines, which sound waves are free to interfere with one another if of unequal periods and so give lrise to beats indicating that the speeds at which the machines are running are not yet equal. When the beats disappear and the tonesettles down'into a steady note it is because the sound and current waves of the different machines have become of equal periodicity, and the machines may thenbe coupled together. In the sameway harmony in phase may be detected, for though there will be no beats at all times when the periods of the waves are equal, yet the intensity of the resultant tone will be greater or less according to the degree of harmony in phase. The current waves are reproduced in properly corresponding sound waves by the magnetic eifects of the current, each current wave imparting a magnetic impulse to a magnet which in turn controls the vibration of thediaphragm.

The drawings illustrate apparatus by which the invention has been put into practice, but it is capable of wide modifications. I have even found that lack of synchronism between two neighboring machines may be detected by the tones given by ordinary reeds set into vibration at speeds respectively proportional to IOO applied to a circuit where two generators are coupled in multiple. Fig. 4 shows the indicator arranged to detect when a motor is in synchronism with a generator which is to drive it, and Fig: 5 shows a longitudinal section of a slightly modified form of construction.

The indicator A, as shown, is of a design suitable for use with two machines. It consists of two or more metallic diaphragme or vibrators A', each of which is to be set into vibration so as to give rise to a distinctive series of sound waves corresponding to and representing accurately the current waves of one of the machines tested. The diaphragms are shown fastened to, and closing up the ends of, a sounding chamber B having an opening B. Magnets C are, in Fig. l, mounted on plates D outside the sounding chamber with their poles in intimate magnetic relation to the diaphragms, and can be adjusted nearer or farther away from them by set screws E.

How the indicator is coupled up in circuit is shown in Fig. 3. Here F, F are two alternating current generators. When running they are normally coupled in multiple with a single work circuit G, and switches H, H, which may be controlled by a common lever I, are placed in the connections between the machines and the work circuit The two magnets G, C, respectively, are included in the secondary circuits of transformers J, J ,whose primaries are connected with the dierent generators F, F. The magnetic impulses in each magnet, therefore, will correspond rigidly with the current waves of the corresponding machines at any given moment, and these magnets acting upon the respective diaphragms will give rise to series of sound waves, which waves will be equal or unequal in period according as the speeds and current waves of the machines are or are not equal. If unequal the resulting beats are very pronounced and the machines should not be thrown together until a steady resultant tone is given. Until synchronism is attained the circuit of one or both of the machines will be broken at the switches H, H.

In Fig. 4 F represents an alternating current generator having in its circuit the primary of a transformer J,whose secondaryincludes, as before, one of the magnets O. K is an alternating current motor which is to be driven with current from dynamo F. The connecting circuit between the two machines passes through aswitch H and maybe opened or closed thereby. In the circuit of the motor is the primary of a second transformer J', the impulses of current in which aect the the second magnet C, and vibrating diaphragm. In order to start these machines` into normal operation the dynamo will be brought to speed with the circuit opened at H. The motor K will also be brought to speed by an auxiliary motor K belted or connected thereto, the motor K meanwhile acting as a dynamo. When synchronism is attained motor K will be disconnected, and the circuit connecting the machines F and K closed. If desired these two actions may be effected s1- multaneously by a common lever S, which works a reciprocating bar S to which is connected the main circuit switch, and` which also controls a belt shifter throwing the motor K out of gear with K.

When the machines have been brought to synchronism, the transformers and indlcator will preferably be cut out of circuit, and w1ll remain cut out, since when once startedthe machines,will continue to run in synchronism, and there is no further need for the indicator.

The construction in Fig. 5 is very similar to that in Fig. 1, except that it is preferred to have, as there shown, the magnets as well as the diaphragm inclosed within and protectedby the sounding chamber. The pole pieces of the magnets are screw-threaded and are screwed into the end plates of the sounding chamber so that the magnets are supported and may be readily adjusted toward and away from the diaphragms by turning the magnet cores.

What I claim as new, and desire to secure by Letters Patent, is

1. The method of indicating synchronism or lack of synchronism between two or more machines of the alternating currenttype, which consists in setting up sound waves corresponding in periodicity with the current waves of the respective machines,which sound waves are free to interfere with one another IOO and give rise to beats if of unequal periodic- 4 IIO rent waves of such diierent machines, which r sound waves by their interference, if unequal in period, give rise to beats, and thereby indicate audibly the presence or absence of syn chronism, as described.

3. An indicator for indicating synchronism between two or more alternating current electric machines consisting of diaphragms or vibrators in an acoustic medium, and means whereby each machine imparts to a corresponding diaphragm or vibrator, vibrations corresponding in periodicity to the current waves of such machines, for the purpose described.

4. An indicator for indicating synchronism or lack of synchronism between two or more alternating current machines which consists of separate magnets responding respectively to the current waves of the di erent machines, and a magnetic diaphragm in intimate magnetic relation to each such magnet, whereby equality or inequality in the periods of the sound waves caused by the diaphragms may be detected by the ear to indicate synchronism of the machines.

5. An indicator for indicating synchronism between two or more alternating current machines consisting of magnetic diaphragme placed opposite one another in a more or less confined sounding chamber, a magnet in intimate magnetic relation to each diaphragm, and circuit connections from the different machines whereby the magnet impulses in the magnets respond accurately to the current waves of the respective machines.

6. The combination in an indicator for the purpose described, of transformers the primaries of which Vrespectively are in circuit with the machines, and magnets connected said magnets by reason of their connections with the machines. Y

In testimony whereof I have hereto set my hand this 20th day of December, 1892.

LOUIS BELL.

Witn esses:

N. F. HAYES, C. L. HAYNEs. 

